Error when I render to RTX
I am rendering with multiple RTX2080ti GPU's in a windows 7 pro system and I am getting very good and stable results.
What I did was the following;


Download the latest experimental 2.79 version that supports RTX.
Replace the complete content of the C:\program files\blender foundation\blender 
folder with the experimental 2.79 version. This will force windows to treat the 
experimental version to run as an installed application, much better results!
Do not use the latest Geforce driver but find and install version 417.35


Good luck!